THE CLOUD OF UNKNOWING - CHAPTER 61
That all bodily thing is subject unto ghostly thing, and is ruled thereafter by the course of nature and not contrariwise.
Mind over matter, there's a lot that has been said about that over the years. Some of it is very sound and some leads to trouble. It seems that in the Orient, there's almost the opposite idea. By that idea, if we adopt physical postures and such that express the mental attitude we seek, we'll acquire that mental attitude. They have no monopoly on that approach, "High" church liturgy and rites are the same idea, act in such a way as will put you in the frame of mind appropriate for worship. Maybe there's something like "in or out" here, our author is working from the other end. He gives the example of our physical posture improving when our soul is effectively disposed by the exercise or work described in The Cloud.